RIbcraft 7.8 auxiliary

Ally S · 08 April 2010, 15:25

We managed to sell our redbay over the winter and, after a good bit of research, including a long trawl through the ribnet "which rib is best" threads, we have placed an order for a 7.8m ribcraft professional, which is currently in the mould at the factory.

The boat will be based in Oban so we really do need an auxilliary engine - if anyone has a ribcraft 7.8 with an aux and can shed some light on what size they run and how suitable it is that would be much appreciated. I know strictly speaking we should have something around an 8 but it would be good to have an integral fuel tank, which limits us to a 6hp i think.

Any advice gratefully received!

Nos4r2 · 08 April 2010, 17:53

Quote:

Originally Posted by Ally S

it would be good to have an integral fuel tank,

Why? Are you going to have an inboard diesel?
Far better to put an extra fuel connector on so you can plug into the main tank. You won't get far on an inbuilt tank.

Ally S · 08 April 2010, 17:59

Ideally it would have an integral fuel tank and also a connector so we could do either - that way if there was a problem with the fuel in the main tank rather than the main engine then we could still get home, but i take your point you dont get very far on an integral tank!

Maybe we just need to get a bigger engine and keep a sep 20l tank onboard somewhere to connect up to the aux if needed.

I think it all comes down to whether or not a 6hp would be sufficient to make any headway in a boat of this size or whether we will need to go bigger.

TUFTY · 08 April 2010, 18:01

I would always have a completely independent fuel system for an aux engine. The problem which caused the main to fail could be fuel related which may cause the aux to fail also. Anyone have a view on this?

Cheers

Paul

NautiSeacrets · 08 April 2010, 18:13

Bit cheeky................but I have a 6hp Mariner 4 stroke going up for sale soon.

Only a year old, done less than 10 hours I reckon.

It has remote tank, although I'll keep that for spare fuel.

Nos4r2 · 08 April 2010, 18:18

Quote:

Originally Posted by TUFTY

I would always have a completely independent fuel system for an aux engine. The problem which caused the main to fail could be fuel related which may cause the aux to fail also. Anyone have a view on this?

Cheers

Paul

There's pros and cons to it.In theory it's a good idea but it's a big lump to have a second separate tank lying about. You've got to remember to cycle the fuel in it or it'll go stale.

Use a decent fuel/water separator/filter unit and there's no reason to have a problem unless you're not checking stuff properly or you're daft enough to run out of fuel.

Neil Harvey · 08 April 2010, 19:54

OK, son on a 7.2m Shakespeare, a 9.9 Tohatsu only pushed me along at about 5 knots, full throttle with no tide. Changing the prop might help a bit I guess, but I'd definitely go bigger than a 6, and would prefer a 15 on mine if I had anywhere to fit one!

Chris · 08 April 2010, 20:37

That's a fairly big rib to push with a 6hp, I would be looking at some of the lightwieght fourstrokes like the Tohatsu 15hp or similar.

9D280 · 09 April 2010, 10:53

Or, at risk of opening the usual can of worms and starting the usuial arguments, go twins for the main engine?

Having said that, if it's in the mould may be too late to specify a "straight" transom, and assumes you havenlt already ordered the juice burner......

(Usual comments about flly independant stuff applies)

ribdraft · 09 April 2010, 12:44

hi ally, i just bought 7.8 ribcraft before christmas, funny enough i put an offer on your boat at same time thru redbay,ended up with ribcraft in end, small boating world! anyway i've a yam 250 four stroke with a 6hp suzuki aux, it works pretty good , i was surprised how well it worked, and to be honest i'm not sure if a bigger one would fit as its very tight with the 6 , anyway will be out on it tonight so if you have any Question or want me to test it in anyway let me know,wil take few pic for you too

Ally S · 09 April 2010, 13:22

Ah small world indeed!

Some pics would be great - if you could take a photo of how it sits on the transom that would be ideal. We have gone for a 300 suzuki so will have the same space issues. I presume you can still get full lock both ways on the big engine?

If you could let me know how it pushes her along speed wise that would be great - we get some pretty fruity tides round where we are but it would really be for emergencies only so as long as it can get us to the nearest shore eventually that would do.

Did you go for integral fuel tank or sep?

Cheers
Ally

ribdraft · 09 April 2010, 13:41

i'm just going taking it out now, so wil take few pic's , i near sure that greg had a 6 hp suzuki, on vampire and there is another 7.8 called maverick ,you find threads on them here too, which was both 300hp suzuki, anyway know matter which way you turn them they don't touch, will send pic's tomorrow

bedajim · 09 April 2010, 15:39

I have a 6.5 m Vipermax and have a 15hp 2st aux

It sits a little high on the transom (but I'll make a new bracket for this year) but pushes the boat along at 7 knots very easily, I've towed a 7 m Vipermax with it to get us both out of shallow water and we still got 4 knots. I have a 22 litre tank on deck behind the rear jockey seats and it's not a problem

Jim

Mollers · 09 April 2010, 16:41

Quote:

Originally Posted by bedajim

I've towed a 7 m Vipermax with it to get us both out of shallow water and we still got 4 knots.
Jim

It was a strategic decision to exit by means of the aux whilst on the Scillies, not a f'k-up. Honestly.

bedajim · 10 April 2010, 06:31

Quote:

Originally Posted by Mollers

It was a strategic decision to exit by means of the aux whilst on the Scillies, not a f'k-up. Honestly.

You mean my 15 hp gearbox + prop is cheap to replace compared to a 200 + 250

ribdraft · 10 April 2010, 11:19

can't find the lead to upload photos from phone to laptop so i'll post later, we were gettin bout 4.5 knots out of it, thats with 2 on board and half tank fuel [130 litres] it was blowing a good 15kts of wind and quit choppy .hope that helps

Mollers · 10 April 2010, 12:41

Quote:

Originally Posted by bedajim

You mean my 15 hp gearbox + prop is cheap to replace compared to a 200 + 250

Cheap for me.

pvm · 11 April 2010, 19:59

our ribcraft 7.5 wears a suzuki 250.

we use a yamaha 8hp 2-stroke as auxillary engine.

does about 5 mph comfortably, probably a bit more with the throttle max open.

fast enough to get you out of trouble, and easily de-mountable to go on our folded avon tender.

doesnt seem to make much difference to speed if you lash the 8 hp straight, and leave the 250 hp in the water (in neutral) so you can sit down and steer with the helm.

philip

GordyP · 12 April 2010, 13:35

Or as someone else has suggested put twin engines on, you will still be able to get home a decent speed if something happens.

Ally S · 12 April 2010, 15:56

much as i would love to go for twin engines for the safety benefit the extra cost was too much sadly. Looking like we will go for a suzuki 6hp - might not get us rocketing home but should hopefully see us right. Will also go with the black, black and more black colour scheme, which is of course crucial!!

Thanks to everyone for their input - boat going into mould as we speak i gather.....